A crabsnatcher is someone who snatches crabs off pubic hair, for sport or pleasure.

Could also be a person that has uncanny abilities of diving into water , generally with a sandy bottom, and manually yanking crabs from other peoples crab traps and/ or cutting their crab pot's line so that only they will successfully pull crabs from the water.

That chick he met is nasty; he will be a crabsnatcher before the nights over.

The crabsnatcher ruined everyones fishing...i assume it was the guy in scuba gear that came up with a bunch of crabs, despite having no crab pot.